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Member postings for Howard Lewis

Here is a list of all the postings Howard Lewis has made in our forums. Click on a thread name to jump to the thread.

Thread: Piston Ring
17/03/2017 07:28:00

Having spent my working life (starting as an Apprentice in 1958) developing and trouble shooting diesel engines, be assured that piston rings ARE designed to be gas backed. Running on light loads, friction is reduced, and quite often blowby can increase, but on full load the ring makes a better seal.

Blowby can also be affected by ring gap. The smallest gap that is acceptable, and workable is the one which JUST prevents the ends of the ring butting together. If the ends butt at full load conditions, the ring will break, often resulting in damage to the bore and the piston.

Howard

Thread: rotary table problem
08/03/2017 15:54:30

Glad that you have overcome the immediate problem.

But, for the future, if you can, it would be ideal to find a means of resetting the 2MT bore on the centreline. Using the 2MT bore can be very useful for various tasks.

Judged by what you have said, so far, it seems unlikely that the Table is running eccentric in its bearings.

I would suggest clocking the 2 MT to find , and mark the sleeve and the table, WHERE it is eccentric, and noting by how much. Scribe the line hard, you may need it later.

It has been suggested to press out the 2MT sleeve fitting; then:

1) You can check if the locating OD and the 2MT bore are concentric. If they are, the problem lies with the bore in the table. (Vee Blocks and DTI or set the OD to concentric in a 4 jaw chuck before clocking the 2MT bore).

2) If the table bore is eccentric.

This can be fixed by boring the Table oversize, but off centre. (If there is sufficient metal around it) The depth of cut will vary until the eccentricity has been removed and the new bore cleans up all round. You then decide how much larger to make the bore for a sleeve to match the new bore to the OD of the 2MT sleeve. .

Set the bore to run true. Then move the bore off centre, in the opposite direction to the marked direction by half the measured eccentricity

You then bore a sleeve to be a tight fit on the 2 MT sleeve, and without changing anything (to keep the two machined surfaces concentric) turn the OD to be a tight fit in the enlarged bore in the Table.

Theoretically when you assemble everything the 2MT bore should now be concentric with the Table.

If you find that the 2MT bore is eccentric to its OD, you either need to turn, or more likely, grind the OD to make it concentric, before enlarging the bore in the table and turning up a sleeve to unite the reduced OD of the 2MT sleeve and the enlarged Table bore.

The real bodge would be to open up the bore in the Table, before turning a sleeve to be a tight fit, and then boring to be a tight fit on the 2 MT, BUT ECCENTRIC, so that when everything is reassembled IN THE CORRECT ORIENTATION, the 2MT bore then becomes concentric with the table.

However you fix the problem, it may useful to coat mating surfaces with Loctite or some other anaerobic locking fluid, to fill the tiny gaps in the machined surfaces, and to prevent any movement in future. If you choose the eccentric sleeve route; do get the orientation right. Once the anaerobic has cured, you will find it difficult, if not impossible, to press things apart, to reset the alignment.

Hope that this is some help.

Howard

Thread: Are we the last generation.?
08/03/2017 12:44:19

No doubt, our numbers will decrease, but manual machinists will not become extinct for a while.

Model Engineering Clubs, the Traction Engine Trust Steam Apprentice scheme, and so on, will nurture a few younger folk into the black arts. Some clubs are fortunate enough to have thriving groups of younger members.

We can all tell tales of how something "beyond repair" can be fixed.

(That s how JS makes his living! More power to his elbow.)

So by bringing in younger folk, and passing on our skills, they learn useful trades, and gain a vast a mount of personal satisfaction from seeing the end product. The JOY of proving wrong the person who says "That can't be fixed"

In 1977, I was told that a master plumber, in the US could name his price, presumably because of the shortage of practical skills. We were told by specialists that a faulty control system needed a 10 Ohm, 10 watt resistor to fix, and there were none around.. Two limey mechanical engineers suggested strapping together ten 100 Ohm 1 watt resistors. The system was up and running within hours!

Must be even worse now, judged by what happens currently in UK.

As long as vintage products are around, there will be a need for people with the ability to mend/ repair/make replacement parts. Having said that, I doubt if our modern all electronic controlled devices will be around.

The plastics will degrade, and the other components will be superceded. ( Unless someone can find a way of replicating the ICs with individual components on pieces of vero board).

At least 3D printing gives the chance to replicate failed plastic components, and engineers practical skills should allow new parts to be machined.

There's hope for the world, yet

Howard

Thread: Cylinder bore surface?
03/03/2017 16:35:30

The other thing with Flexhones, is to CLEAN everything afterwards, I think that they advocate scrubbing with a nail brush.

You cannot afford to have particles of Silicon Carbide around. That makes running out compound, not running in!

Howard

Thread: Ex-lurker in S.W France
03/03/2017 16:06:58

At the risk of being though tight, rather than careful, why not make a stand from angle iron? Gives the opportunity to include storage drawers as well. Include tappings in the feet to aid levelling if you wish.

Clad it in sheet steel and paint it to make it really bespoke.

You'll need a crane or some strong friends to lift the machine onto it when complete; unless you enjoy jack and pack routines.

Howard

Thread: 51 x1/2 Bandsaw Tension
03/03/2017 16:01:21

Another, non My Time Media, UK, M E magazine had an article on making a tension meter, a few months back.

It used a DTI to measure the blade extension as it was tensioned. Other than the DTI and the Silver Steel pivot and a few small capscrews, it all came from a bit of square bar (15mm from memory)

I made one and used it to set blade tension on my elderly 4.5" bandsaw. Since then no broken blades, and seemingly improved accuracy. The first trial cut off a bit of 38mm round bar, suggested a variation on thickness of about 0,025mm on a 1.5mm thickness. But I don't expect that degree of accuracy!, purely a one off!

So, in my book it is a very useful, but rarely used, device.

Have you checked that all the guide rollers are correctly set and aligned?

The shorter the blade, the more sharply the blade twists as it enters or leaves the wheels. Before the 4.5" I had a little one, and was lucky to cut one piece of 38mm angle iron before the blade broke, despite being carefully set up. Needless to say that went back!

Howard

Thread: Oil coolant pumps - which type of pump
03/03/2017 15:44:59

If using an ex washing machine pump, the risk is that neat oil will almost certainly degrade to O ring seals. May be longer lived with soluble oil; but do check. Could be worth replacing the standard O rings with EPDM, or Silicon ones. May be relatively expensive, but you are probably only looking at a couple of seals most times, not dozens. Being centrifugal should cope with the odd bit of swarf.

Some washing machine pumps need the impellor to be kept against the housing, or leakage around the back of the impellor reduces efficiency a lot.

Gear type pumps will not tolerate swarf or particles because of the minute tooth/tooth and gear/endplate clearances. And do you really need high pressures? 4 bar will throw oil several metres. and all you want is to prject it about 100mm, which can be achieved with little pressure

(My soluble oil is gravity fed (via a syphon) from less than a metre above, through 8mm OD windscreen washer tubing, through a needle valve to reduce the flow to a steady drip. Obviously, if you want a high flow to flush away swarf, you need a continuous flow, but probably not at any pressure greater than 0.75 bar (10 psi in old money)

A diaphram type punp has been used for soluble oil on chopsaws. The diaphragm may well tolerate neat oil. The pressure is determined by the spring (That does the pumping; the eccentric merely pulls the diaphrgm down to fill the pump, compressing the spring in the process) If the valves are mica or tufnol there should be no compatability problems, but watch out for any O ring seals. As pump intended for petrol or diesel (gas oil), the seals should tolerate neat oil.

Most diaphram lift pumps only deliver 3 -5 psi. One from an in line injector pump may provide 10 psi.

The suction lift should be no greater thant six feet, (aim for minimum if possible) which should be adequate for workshop use.

Swarf in the valves will prevent it pumping, for obvious reasons.

Being intended for low viscosity oils, heavier oils may decrease flow whilst subjecting the diaphragm to higher pressures, which will decrease life. Rebuild kits used to be available many years ago, but modern pumps tend to be Kleenex "Use 'em. Throw 'em" types with the edge of the steel top rolled around the lower body.

Presumably, a SU electric pump should work O K., but a 12Volt supply needed, and they are not intended to run at full speed for long periods, rather more intermittently.

Howard

Thread: Anybody know what these are ?
03/03/2017 15:12:01

With regard to bolt stretch, the most efficient use of a fastener is to tighten it to JUST put the material into yield. We used to tighten W Range 1/2 UNF bolts so that they took on a permanent extension of about a couple of thou. By this time, the load in the bolt was circa 9 tons. And we found that the bolt could be retightened in this way 6 times or more, so we advised 4 times in the field, before replacement was necessary.

The machine monitored angular rotation vs torque for each spindle.  When the previous angle/torque relationship began to increase, it sensed yield and stopped rotating

To see the machine tighten 32 bolts from finger tight into yield, in barely 7 seconds , was quite impressive.

Lots of vehicle manufacturers now tighten the important fasteners into yield.

Howard

Edited By Howard Lewis on 03/03/2017 15:14:04

Thread: Source of neat cutting oil
03/03/2017 14:56:01

I don't think that Warco will supply by post/carrier, except with a machine. You can buy / collect from their stand at shows.

Would not have thought that EP90 would be a suitable cutting fluid. The Extreme Pressure feature could well prevent the tool forcing its way through the oil film.

Even neat cutting oil will show this at times with a very fine feeds. The tool advances , barely cutting, and then the swarf comes flying of for a short time, before the process repeats itself.

Howard

Thread: Slip Guages, and Setting a Quick Change Tool Post to Centre Height
27/02/2017 16:39:13

Two comments:

Boxes of slip gauges (Matrix - Coventry) used to contain a piece of chamois leather with which to wipe the slips,. (Paper towels can be abrasive, and we are dealing with items mirror finished to better than a millionth of an inch.

At the Sentinel Works of Rolls Royce Oil Engine Division, our ex Sentinel Instructors advocated the clean ball of the thumb as an alternative, before wringing the slips together, or separation by rotating them.

They also drummed in to us ALWAYS to use the Protective slips on each side.

Howard

Thread: drill chuck fitting
27/02/2017 16:25:02

Details of Jacobs standard tapers are shown on page 3.5 of Tubal Cain's Model Engineers Handbook, 3rd Edition.

Issue 10 of the ArcEuroTrade Catalogue, Page 7 shows Chuck Removal wedges, covering JT1, JT2, JT3, and JT6, sold as pairs.

At the top of page 97 there is a comprehensive table giving details of Jacobs Tapers, 0,1,2 Short, 2, 33, 3, 4, 5 and 6, and then DIN tapers, B10, B12, B16, B18, B22 and B24 .

If your small drill press is anything like the Power Devil one that I use to own, the chuck shouldn't need much to remove it. Mine fell out!

Howard

Edited By Howard Lewis on 27/02/2017 16:26:36

Edited By Howard Lewis on 27/02/2017 16:27:04

Thread: Chuck binding
27/02/2017 16:00:32

Often, deburring, (or even slightly relieving the sticky one) the slots in the chuck body will bring about a big improvement. There may even be some bright spots to tell you where to direct your activities.

Howard

Thread: 4 facet drill sharpening jig plans
25/02/2017 20:01:43

SORTED!

The PC would display the PDF, but not download it fully.

Managed to print it, and then I spotted a "Save As" button , Lo and Behold it down loaded.! Rename and ready for another print when the first gets covered in greasy handprints, as it surely will.

Must be something to do with old dogs and new tricks.

Howard

25/02/2017 18:48:50

For some reason, my system will only download page 1. After that "There is a problem"

Any ideas, please?

Howard

Thread: Securing threaded backplate
25/02/2017 18:09:25

Milking maids, or their 3 legged stools, are barred from my shop! (says he sheepishly)

But to be serious for a few seconds.

My oriental lathe with screw fitted chucks uses two clamps fixed to the back of the chuck to hook behind a chamfered flange on the mandrel, to prevent the chuck going AWOL when running in reverse..

Suggestion for the brave and innovative.

IF you could make up a split ring, with a chamfer on the back face, and clamp it to the plain dia behind the register, maybe a couple of "hooks" could be attached to the back of the chuck, to prevent the chuck unscrewing on the odd occasions when you run in reverse.

Drill/tap two largish dia shouldered "studs" into the backplate, on a diameter, and tap the outer end of the shoulder, radially, to take the screw fixing the "hooks"?

When I had a ML7, it lacked this feature, but by GENTLY tightening the belt, and taking light cuts, (never tried screwcutting - where the cuts are likely to be heavier) it was possible to run in reverse without the chuck coming loose. Maybe I was just lucky.

Howard

Thread: Clutter in lathe swarf tray
25/02/2017 17:39:06

What wonderful, organised, disciplined folk you all are!

The shelf just above and behind the lathe carries drill chucks (Am sure that mine breed!) rotating centre, faceplate, catchplate, steadies and mandrel handle. A plywood tray on the headstock cover carries chuck keys, Parting tool holder key, a couple of spanners, a T handle Allen Key (for the removable chuck guard) and bits of metal that I am too idle to put away. How did the knurled Aluminium knob get there?

Drill boxes, and boxes of Taps and Dies live on a shelf on the other side of the shop, with a box of miscellaneous Tap wrenches and Die holders. So close that they are accessible just by turning around.

There is almost no space on the fitting bench because of all the drawer units holding the various sizes of nuts, bolts, washers spare taps, knurling and deburring tools.

On a good day I can lay hands on what I'm looking for!

No wonder I work in the prototype for Rubiks Cube.

Howard

Thread: What Did You Do Today (2017)
25/02/2017 17:04:37

Thanks for the comments re insurers.

Funnily enough, the following morning, at 0800 had a call saying "Your insurers have told us to collect the car"

" Hold your horses, we haven't agreed the value yet, Call me back in a week"

Friends have had similar experiences. When my daughters car was torched, they started acting quite aggressively, as if they owned the car. Again, before the price had been agreed. In contrast, my wife's car, written off by someone reversing without looking where he was going, the assessor looked at the car and said "I can't offer you book value. Its too good for that" and offered just over twice as much. (Until this idiot dented the door, distorted the subframe and cracked the radiator, it was an exceptional, rust free 17 year old with lots of life left in it).

Have asked for an independant repair estimate.

However, it might be an easy way of getting rid of an eleven year old , and betting something more upto date, that is easier to load (4 door instead of 2) for taking exhibits to shows. Only worry is the effect on the bank balance!  (The courtesy car probably started me thinking that way)

At least the tree didn't injure my wife or myself, so things could have been a lot worse.

Howard.

Edited By Howard Lewis on 25/02/2017 17:05:29

Thread: Best way to cut stock to size
25/02/2017 16:40:37

Despite owning a couple of angle grinders, my preference is for the horizontal/vertical 4.5" bandsaw. Mine was made on a Friday afternoon before being shipped to Warco. The very thin tubular spacer between the bearings on the wormwheel shaft split and went through the lower bearing and oil seal. New bearings and seal were fitted, with a thick wall brass spacer. The thin steel spacer behind the Idler Wheel was replaced, similarly, after having trued up the two blade wheels.

The drive/driven pulleys benefited from being aligned, as no doubt did the belt.

Made up a tension meter for the blade, as featured in another UK M E magazine, and a thin test cut was consistent to within a thou! DON'T expect it to repeat that, but the best performance yet. Presumably, judged by that, it is as well set up as can be expected.

The blade seems to last longer, without breaking, or going blunt.

Has been used to cut round bar, square bar, box section, angle iron, aluminium, plastics, and whatever has been thrown at it . Would not be without it since it cuts more accurately than I can, and with almost no effort on my part.

Howard

23/02/2017 21:56:57

Having fried a Bosch angle grinder,(noisy) I got a Makita as part of my retirement present, quite noisy, but still going 13 years later.

Strangely, the very quiet one is the Power Devil that I bought to go in the cheapy stand to use it as a chop saw.

Seems that its gears that make the noise on angle grinders.

Use the 4 1/2 inch bandsaw for most work, or a slitting saw in the mill / drill. Hacksaw only used for jobs that are quicker than getting out and setting up, the bandsaw.

Howard

Thread: What Did You Do Today (2017)
23/02/2017 21:34:35

Does starting an argument with Insurers over not writing off car for the headlamp broken by a falling tree branch, count?

Most annoying was that if we hadn't taken home a sick friend, we wouldn't have been there!

Ah well, life never was fair. Awaiting quote from the local approved repairer, to see if that will change the box ticking corporate mind. Why scrap a car that is not much more than cosmetically damaged, and otherwise good.

Looks like we are going to be in the market for a small car with a spare wheel and a proper handbrake!

Gripe over Workshop time should cheer me up a bit

Howard

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